Medical ultrasound images are typically produced by generating an ultrasonic sound wave traveling in a known direction and observing the echoes created when the sound wave bounces off of boundaries between regions of differing density in the body. For any given direction, the image pixels are generated by plotting a dot whose brightness is proportional to the echo's amplitude at coordinate whose location is a function of the time the echo is received after a short pulse is send in the direction being measured. The process is repeated in different directions, thereby generating a two-dimensional image in which each point corresponds to the sound reflectivity of a different voxel in the patient's body.
Ultrasound images typically include a significant amount of speckling which appears as random noise. This background makes the detection and enhancement of edges of organs and vessel boundaries difficult. Classical edge detection/enhancement techniques such as fixed size gradient operators or the Laplacian of a Gaussan operator are poorly suited to ultrasound images since these techniques also enhance the speckles and tend to widen the detected edges and speckles.
Prior art edge enhancement methods for real-time applications rely on first-order statistics, namely the intensity histogram, to determine the boundaries of edges. Unfortunately, the properties of edges that are most effective in detecting edges require second-order statistics. Second-order statistics place a high computational load on the data processing system, and hence, have not been used for real-time applications.
Broadly, it is the object of the present invention to provide an improved ultrasound imaging system.
It is a further object of the present invention to provide an ultrasound imaging system with improved edge enhancement while not substantially enhancing speckling or widening the edges processed.
It is yet another object of the present invention to provide an ultrasound imaging system in which the edge enhancement computations are within the computational capability of the computer systems normally included in commercial ultrasound imaging equipment.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.